The invention relates to a medical instrument for endoscopic surgery.
Instruments for endoscopic surgery generally include a sheath tube with a connecting body arranged at the proximal end area of the sheath tube, a push/pull rod leading through the sheath tube with an end effector attached to the distal end area of the rod, and a hand grip attachable to the rod for the guiding of instruments and for actuating the end effector. For cleaning purposes and for the ability to adapt to different applications, such instruments are traditionally designed to be disassembled.
For creating a detachable connection between the hand grip and the sheath tube, the hand grip is traditionally attachable to the connecting body via a coupler. The connecting body also serves as a rotary handle for rotating an end effector arranged at the distal end of the rod. For this purpose, the rod is typically non-rotatably connectable to the sheath tube. In such embodiments, the proximal end of the rod leading through the sheath tube can be connected with the hand grip in a positive lock.
An important aspect in the design of the aforementioned type of instruments intended for disassembly is the mechanism for creating a coupling connection between the individual parts. Traditionally, the coupling mechanisms are designed in such a way that the disengagement of at least two parts is carried out by overcoming a spring-loaded locking mechanism. For doing so, a locking slider spring-mounted in a transverse shaft in the connecting body can be actuated using finger pressure. In designing the locking slider, special attention is paid to enabling quick and easy operation on the one hand, and guaranteeing a high degree of reliability against malfunctions on the other. Moreover, the compact integration of the locking slider into the connecting body is desirable for the production of slender, lightweight instruments.
A generic instrument is known from DE 100 64 623 C1, which is constructed from a plurality of parts intended for disassembly. According to this prior art, it can be provided that a locking slider is housed in a shaft of a connecting body and held in place by spring force. For this purpose, it is proposed to arrange a coil spring outside of the connecting body in a direction coaxial to the locking slider, whereby a first end of the coil spring is supported by the periphery of the shaft opening in a wall of the connecting body, and the second end of the coil spring presses against a radial projection of the locking slider.
This manner of construction, having an exposed spring on the exterior of the medical instrument, has proved to be disadvantageous for a variety of reasons. One aspect is the difficulty of cleaning of such instruments. The spring elements arranged on the exterior of the device form a variety of edges and crevices, making it quite cumbersome to clean away germs and residue associated with substances coming into contact with the instrument. Moreover, the hazard exists of body tissue or other material passing by the spring element, for example sutures for the closing of open wounds or incisions, becoming caught on the edges of the spring element. This can lead to the holding mechanism becoming jammed or to difficulties in using the instrument.